Commutating brush



Nov. 6, 1934. c. LYNN COMMUTATING BRUSH Filed Sept. 30, 1932 INVENTOR ATT'oRNEY Patented Nov. 6, 1934 UNITED STATES PATENT OFFICE COMMUTATENG BRUSH Pennsylvania Application September 30, 1932, Serial No. 635,515

6 Claims.

My invention relates, in general, to commutating brushes or the like and more particularly to the manner of attaching a flexible conductor or conductors to a brush.

An object of my invention is the provision of a connection of the class indicated that will be simple and reliable and may be readily manufactured and installed.

Another object or" my invention is to provide for so connecting a flexible conductor to a commutating brush that, should an attempt be made to withdraw the commutating brush from the brush holder by grasping and pulling or jerking the flexible conductor, the mechanical stress is substantially uniformly distributed over a major portion of the brush, thereby avoiding the possible danger of damaging the brush and pulling the flexible conductors out of the brush.

It is also an object of my invention to provide for reducing the current density at the place where the flexible conductor is attached to the brush and thereby prevent excessive heating of the connection.

Also, in those cases where my invention is applied to the so-called laminated brushes having parallel paths to prevent circulating or eddy currents from flowing transversely of the brush, my connection makes electrical contact with substantially all the parallel paths of the brush, and thereby reduces the length and resistance of the current path from any particular lamination to the flexible conductor.

Other objects and a fuller understanding of my invention may be had by referring to the following specification, taken in conjunction with the accompanying drawing, in which:

Figure l is a front elevational view of a brush embodying the features of my invention;

Fig. 2 is a plan view of the brush shown in Fig. 1;

Fig. 3 is a cross-sectional View taken along the line III-III of Fig. 1;

Fig. 4 is a front elevational view on a reduced scale, of the main connecting clip that isriveted to one side of the upper part of the brush; and

Fig. 5 is a front elevational View on a reduced scale of a secondary connecting clip that is riveted to the opposite side of the upper part of the brush.

With particular reference to the drawing, my invention, in general, comprises a brush 10, a pair of flexible spaced conductors embedded or otherwise suitably connected to the brush 10, a main connecting clip 14 riveted to one side of the upper part of the brush 10, and a secondary connecting clip 15 riveted to the opposite side of the upper part of the brush 10.

As illustrated, the lower ends 13 of the flexible conductors 11 may be attached within the upper part of the brush 10 in any suitable manner. In usual practice, the upper part or" the brush is provided with two spaced holes, having a smaller diameter at the top than at the bottom, and being oppositely inclined to the plane of the brush. The lower ends 13 of the flexible conductors are securely mounted within the holes by flaring out the lower strands of the flexible conductors, or by tamping additional material, which may be in the form of small stranded wires or powdered conducting material with a suitable binder, within the space between the lower end of the conductors and the walls of the holes. In the embodiment of this invention, I have preferably mounted the lower ends 13 of the conductors 11 at an angle with the broad sides of the brush. While I have briefly described the manner in which the lower ends of the flexible conductors may be mounted in the brush 10, it is to be understood that my invention is not limited to the method described because any other well known method may be likewise employed.

In order to relieve the embedded connection of a major part of the mechanical stress, I provide for utilizing a main connecting clip 14 and a secondary connecting clip 15 which, when connected to the upper part of the brush, provide a conductor engaging portion under which the two space conductors 11 may be interlinked in a cross-like manner. As best illustrated in Figs. 1 and 3, the main connecting clip 14 and the secondary connecting clip 15 are securely held in position by means of rivets 16. At a point above the top of the brush 10 substantially equal to the diameter of the flexible conductors 11, the main connecting clip 14 is bent over to provide a conductor engaging portion 17 under which the flexible conductors 11 may be cross-inter-linked. As illustrated, the clip 14 may be bent upwardly from the conductor engaging portion 1'7 and then rearwardly, as shown at 18, to provide a substantially U-shaped recess in which an engaging finger (not shown) may be mounted to raise the brush during the starting period only, and to yieldingly bias the brush downwardly against a commutator during the running period. The purpose of the secondary connecting clip 15 is to secure the flexible conductors 11 under the conductor engaging portion 17. After the main connecting clip 14 and the secondary connecting clip 15 are mounted, that part of the flexible conductors 11 cross-inter-linked under the conductor engaging portion 17, is soldered to the two clips. As illustrated, the upper portion of the secondary connecting clip 15 is provided with a notch 20 and the portion of the main connecting clip 14 that is adjacent to the flexible conductors 11 is provided with an aperture 19. The purpose of the notch 20 and the aperture 19 is to allow spaces into which thesolder may flow or run for effecting a good soldered joint between the flexible conductors 11 and the two clips. interlinked under the conductor engaging portion 17, the two loose ends are joinedtogether and suitably connected to a clip 12. I

I find that a brush embodying the features of my invention, in the event that the brush sticks within the brush holder, may be removed by either grasping the flexible conductors l1 and pulling or jerking the brush out, or, in the event that the brush is stuck too tightly and cannot be removed in this manner, by inserting a suitable stick orbar between the two spaced conductors 11 and prying upwardly until the brush is loosened. In other words, the combinationof the embedded connection and the connecting clips 14 and 15 provide a composite connection which is able to stand very rough usage without the flexible conductors 11 becoming loose from the carbon brush.

Another important feature of my invention is that by having a composite connection, the currentdensit'y at. the point of connection is relatively small, which means that very little heat is developed. With a material reduction in the amount of heat developed at the connection between the flexible conductors and the brush,I find that it is. possible to electrically connect the conductors 11 to the two connecting clips 14 and 15 by means of solder, without the solder melting whenthe brushes are carrying the full rated current as is the case when only soldered clips are'used.

Although my composite connection may be applied to a brush of any type, it is particularly applicable to the so-called laminated brushes having parallel paths to prevent eddy currents from flowing transversely of the brush. Such alaminated brush is covered by Patent No. 1,566,990issued to R. L. Henry on October 13, 1925. As shown best in Fig. 3, because of the inclined embedded connections, the current has to fiow transversely of the brush only for the small transversedistan'ce from the sides of the brushto either the connectin'gclips 14 and 15, or the inclined embedded connections.

The inclination of the embedded connection may vary accordance with the thickness of the brush, sothat irrespective of the thickness of theb'r'ush', my composite connection makes contact with substantially all of the parallel paths and, in consequence, the heating of the brush i's're'duced to a minimum, and the current carrying capacity of the brush is increased.

Since certain changes in my invention may be 7 made without departing from the spirit and scope thereof, itis intended that all matters contained in 'the foregoing description and shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I'claim as my invention: 1. The combination, with a brush or the like After the flexible conductors 11 are cross of a pair of spaced conductors each having one end thereof mounted avithin the brush, a clip having anon-ductor engaging portion connected to that part of the brush which is between the spaced conductors, the said conductors being cross-interlinked with the conductor engaging portion and connected thereto at the cross-interlinked portions of the conductors.

2. Thecombination, with a brush or the like of a pair of spaced conductors each having one end thereof mounted within the brush, a clip having a conductor engaging portion riveted to that part of the brush which is between the spaced conductors, the said conductors being cross-interof the conductors.

3. The combination, with a brush or the like,

of a pair of spaced conductors each having one end thereof mounted within an end portion of the brush, a clip riveted to one side of said portion of the brush, an end part of said clip being bent over to provide a conductor engaging portion for receiving the conductors, the said conductors being cross-interlinked under the engaging portion, and a second clip riveted to the other side of the end portion of the brush, the said secondmentioned clip being disposed to secure the conductors under the engaging portion.

4. The combination, with a brush or the like, of a pair of spaced conductors each having one end thereof mounted within the top part of the brush, a clip riveted to one side of the top part of the brush, the upper part of said clip being bent over to provide a conductor engaging portion for receiving the conductors, the said conductors being cross-interlinked under the engaging portion, and a second clip riveted to the opposite side of the toppart of the brush, the upper part of said second mentioned clip being disposed to secure the conductors under the engaging portion, the first-mentioned clip having-an aperture near the conductor engaging portion, said cross-interlinked conductors being soldered to the said clips.

5. The combination, with a brush or the like, of a pair of spaced conductors each having one end thereof mounted oppositely inclined within the brush, a clip having a conductor engaging portion connected to that part of the brush which is between the spaced conductors, the said conductors being cross interlinked with the conductor engaging portion andconnected thereto at the cross-interlinked portions ofthe conductors. V p

6. The combination, with a brush or the like, of a pair of spacedconductors each having one end thereof mounted at an incline within the top part of the brush, a clip riveted to one side of the top part of the brush, the upper. part of said clip being bent over to provide a conductor engaging portion for receiving the conductors, the said conductors bein cross-interlinked under the engaging portion, and a second clip rivetedjto the opposite side of the "top part 'of the brush, the upper part of said second-mentioned clip being disposed to secure the conductors under the engaging portion. I

' CLARENCE LYNN. 

